This invention relates generally to sonic generators and more particularly to a relatively low frequency active sonar transmitter type sonic generator.
Underwater acoustic projectors are generally well known. In order to reduce the size of low frequency underwater acoustic projectors, one known approach is to increase monopole volume velocity by increasing displacement of the radiating surface. When a low frequency sonar projector of the known prior art is driven by a linear electromagnetic actuator, then large relatively high velocity displacement of the radiating surface requires the use of linear motion bearings and sufficient compliance of the radiating surface periphery. These requirements, irrespective of whether or not the linear electromagnetic actuator is of the homopolar or variable reluctance type, result in the following undesirable results: (a) unwanted noise and heat generated by bearing components, (b) the shunting of acoustic energy away from the load by peripheral compliances, and (c) the constraint of operating depth due to the limitations of the necessary pressure compensation elements located internally of the transducer housing.